This invention relates to a mobile tunnel surface cleaning machine of the type that may be used in performing maintenance cleaning of vehicle highway tunnels. In order to reduce the cost, time, concern for safety and upgrade in quality and efficiency in periodically manually cleaning the sides and ceiling surfaces of highway tunnels, for example, tile surfaces, it has become the increased practice to employ truck like vehicles having some form of a manipulative brush assembly for performing the cleaning operations.
In an earlier form of a mechanical system, attempts were made to use a brush assembly of the type commonly utilized in automatic drive through car washers, which relied, to a great extent, on the centrifugal force of a rotating brush. This system was found to be ineffective due to the fact that the brush bristles are positioned only by centrifugal force and was substantially ineffective to produce a scrubbing force when the brush was forced against the tunnel surface to be cleaned, which it turn created an unbalanced rotational condition for the brush.
Many of these vehicles are provided with brush assemblies mounted on the back of the vehicles, the vehicles in any event being usually manned by two persons, one who drives the vehicle, the other who operates the brush assembly. In this way the vehicle is driven very slowly along one of the lanes of the highway, in a manner that the brush assembly is brought into contact with the tunnel surface to be cleaned with the aid of sprayed hot water, liquid cleaner or detergent and a rinse. While such machines represent a significant improvement over the manual operations, they have not met all of the above objectives.
One of the limitations of present day mechanical designs is the inability to arrange the brush assembly to apply a constant high and effective brush pressure and in doing so to avoid the reaction force taken by the truck preventing the obtaining of the desired brushing action. In past designs this reaction force has been found to push the truck out of its proper traveling path or tend to tilt the truck, thereby causing a drop in the brush pressure and development of an uneven brush pressure condition. In other cases, because the brush assembly is mounted at the rear of the truck, where most of its weight is located and the brush assembly operates adjacent the rear of the truck, when pressure is applied by the brush assembly the reaction force on the truck tends to tilt the truck about its rear wheels, thereby creating a condition where the brush pressure is lowered and it is impossible to control brush pressure.
Another limitation of present day mechanical designs is their inability to create a condition where the water used in the cleaning is maintained at a desired heated temperature when applied to the surface to be cleaned. This leads to a second problem of having to use high concentrations and high volumes of cleaning acid used to clean hard to clean areas of the tunnel, which use creates environmental clean up concerns.
In present day machines even when hot water is used to affect cleaning, the sprays are either arranged a considerable distance from the surface to be cleaned so that the heat of the water is lost by the time it contacts the surface. In addition their is no way to contain or enclose the water during the brushing action to prevent loss of water heat by radiation and escapement or effectively using the friction heat of the brushing action to maintain the water at a desired temperature. Because of this the use of acid becomes necessary and with it the environmental associated clean up problems.
As to the concern of upgrading the quality and efficiency of the cleaning operation, one of the principal problem that must be overcome in present cleaning machines is that presented by the construction characteristics of the tunnels, for example, the various contours of their surfaces, the condition of the tile or other surface material, and the presence of protuberance and recesses in the surfaces in the form of lights, conduits, radio antennas, etc.
The common practice of having the brush assembly operate out of and adjacent to the back of the truck creates the additional problem of the driver and brush assembly operator not being positioned to sit next to each other and therefore not having a common view of the same working area at the same time and which does not permit the workmen to see the working area immediately after the area has been cleaned, instead they see the area only after the truck and brush assembly has past beyond the area. At this point it is to late to make any corrections in the cleaning operation.